Natural Gas Orifice Size for Weber Genesis II E-310 Conversion


 
D

DNemers

New member
Hi all!

I'm new here and recently purchased a Weber Genesis II E-310 in LP but just moved to a house that has a NG hookup so obviously I would rather use that. I have read many of the threads here and on other sites and understand that the best way to convert to NG would be to replace the manifold, however I want to start with the regulator and orifices first before replacing the entire manifold and spending the money.

I already have a 4" W.C regulator, and based on this conversion chart, in order to achieve 13,000 BTUs per burner (39,000 BTUs total), I would need #50 orifices with a hole size of 0.07". Has anybody ever completed this conversion successfully that can confirm this? Also, if anyone knows where I can purchase the orifices relatively affordably in Canada, that would be greatly appreciated! Otherwise I am just planning on purchasing some LP ones from Amazon and drilling them out to 0.07".

All and any help or guidance is appreciated! Thanks in advanced!
 
I know given that you dropped off that PM you started what you got from me information wise was not what you wanted. But, pretty much it's what you will get from most any of us. Weber (unlike other makers) seems to be all over the map when it comes to their manifold assemblies. So sadly you MIGHT have one where by a simple orifice change out, proper supply is given and voila you have a safe and useful grill that works. Or you might have one after that "attempt" in which your low/medium flame settings are not consistent enough to "hold" a flame without a "flameout". This is where an amateur conversion can go VERY sideways. And also become a dangerous issue. Because IF you have that result, and are unknowingly using it like that, just because the flame may be out on a burner or two does NOT mean gas is not flowing. It is! Now you may have all 3 burners on, one or 2 may be struggling or not lit at all. Gas is slowly building up under the hood and you go to check your creation and "whoompf" you have a fireball in your face. Because the sudden rush of O2 and change in air movement may cause the gas buildup to ignite suddenly. You can poo poo this all you want. BUT, I have seen it happen. So you can "cheap out", take a chance you have a manifold with valves that will work and IDK you may have a 50/50 chance? I don't know enough about the newer generation of Weber grills to know what to tell you to look for. I DO know however that the the principals of gas technology don't change nor does the principal of safety.
Not everyone is lucky enough to have a fully licensed fitter train them in all this either as I did after my first failed attempt.
Now that being said. It's YOUR grill, it's YOUR safety (not mine or anyone else's here), and if you feel you'd rather risk your grill and safety to save a couple $$$. Go right ahead. Or you can simply do it right the first time and take the safer more effective road. Honestly it's up to you. If I was standing right there doing it with you, I know what to look for if it hasn't gone right and I know how to remedy. But, I am not standing there. You're lucky in that you actually can find the actual parts to do it CORRECTLY. Maybe count that as a blessing and do so. Worst case you now have a spare manifold in case you need to or want to go back
 
@LMichaels thank you for your advice! I truly appreciate that your extensive knowledge in the subject and it is valuable information. I am fortunate enough to know a licensed gas fitter who advised me just to replace the orifices and regulator, as he did the same with his Weber (same model as mine). If this does not work properly, then I will swap it back to LP.

In this case or even if I do replace the entire manifold, I am just looking for the correct orifice size so that I can ensure that I am doing it safely and properly.

Thanks again!
 
DNemers said:
@LMichaels thank you for your advice! I truly appreciate that your extensive knowledge in the subject and it is valuable information. I am fortunate enough to know a licensed gas fitter who advised me just to replace the orifices and regulator, as he did the same with his Weber (same model as mine). If this does not work properly, then I will swap it back to LP.

In this case or even if I do replace the entire manifold, I am just looking for the correct orifice size so that I can ensure that I am doing it safely and properly.

Thanks again!
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If the person is a lic fitter he'll know exactly what you need. He should be able to actually buy you "spuds" then set the grill up to work either with or without a regulator. He can measure your actual gas pressure, then calculate what's needed. The only reason a regulator is sometimes there is to make sure the pressure stays a little more even. If you have good supply you likely will not need one. Your friend will know this. And again, not every grill will have the correct valves to pull this off. It's not that changing orifices is not "sound" it's just that Weber seems to go out of their way to make it a crap shoot. Once orifices are fitted he will need to be watching you have proper flame propagation across all the burners when it's on low/med. That is where the trouble lies with these grills. If you're running wide open, it doesn't matter. But, again just because someone else had success does not mean you will
 
@LMichaels Thanks again! After reading your post and advise, I am trying to source a manifold, although my question still stands. Are you able to help me with the orifice size? According to this chart and my research, I need a 0.07 inch hole size, which in Canada would be equivalent to 1.8mm drill bit. Does that sound correct to you?


BTUs.jpg
 
This chart is my "go to" for any time I am doing this. https://andersonforrester.com/conversion-chart/ But, oh boy you got me over a barrel trying to equate metric measures to what I know. I'm pretty good on speed/distance and such. But, pressures, and volume (as in MPG vs litre/km) I get a little dizzy LOL. But what you have looks reasonable to me
 
@LMichaels, I don’t want to muddy the waters too much here but I’m assuming the charts shared here do not account for the oversizing of the hole due to runout when drilling. I was taught long ago to slightly undersize my drill bit and then gauge the hole for confirmation, moving up in size until satisfied. Agree? Disagree?
 
TomRc said:
@LMichaels, I don’t want to muddy the waters too much here but I’m assuming the charts shared here do not account for the oversizing of the hole due to runout when drilling. I was taught long ago to slightly undersize my drill bit and then gauge the hole for confirmation, moving up in size until satisfied. Agree? Disagree?
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Yep, I am the same way. I go "under" and work my way up. There are always little inconsistencies when resizing
 
The start smaller and work up is such second nature to me, never thought to mention it. But, when I have used the manometer to confirm pressures and and done the sizing carefully have never had a problem.
 
I should probably mention the “use a drill press, not a hand drill” caveat as well. No one shared that with me and I never gave it a second thought before diving in with my old corded B&D. By the time I was done with that first drill out, I wound up with a hole shaped more like an egg and had to start over with a new blank.
 
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TomRc said:
I should probably mention the “use a drill press, not a hand drill” caveat as well. No one shared that with me and I never gave it a second thought before diving in with my old corded B&D. By the time I was done with that first drill out, I wound up with a hole shaped more like an egg and had to start over with a new blank.
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If I had access to a drill press, I would totally do the same, but unfortunately I don't. I was planning on buying this set from Amazon and just using the included hand drill to drill it out to 1.8mm (0.007").
 
Can't just stick the bit in a regular electric or battery powered drill and go after it?
 
Bruce said:
Can't just stick the bit in a regular electric or battery powered drill and go after it?
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No way that method is going to be precise enough. I can definitely see using the hand drill that Larry linked above to at least start the hole, and then finish with an electric drill. If you are careful enough with the hand drill it might work. A drill press is still better.
 
Bruce said:
Can't just stick the bit in a regular electric or battery powered drill and go after it?
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This is where I went wrong on my first attempt years ago. I used a cheap, plastic housing, corded Black & Decker drill that my father probably paid less than $5 for at a garage sale back in the 70’s. From memory, I’d guess it was a single-speed, 800rpm junker and I can still vividly remember how loudly the gears screamed every time you pulled the trigger. Let’s just say it was not a precision hole making tool in any way. Looking back, I don’t know if it ever drilled a round hole in it’s lifetime regardless of bit size. I’m sure a modern cordless tool would do a much better job but I’ve never tried. I picked up a used tabletop Delta press for $25 years ago and it continues to serve me well for such things. Ironically, I think I paid as much for the accessory drill press vice to hold the blanks as I did for the press itself.
 
Steve Hoch said:
No way that method is going to be precise enough. I can definitely see using the hand drill that Larry linked above to at least start the hole, and then finish with an electric drill. If you are careful enough with the hand drill it might work. A drill press is still better.
Click to expand...
I use the hand device for the whole job. Since I only take a little at a time. It works just fine. Never had an issue. As long as you're careful and methodical it works. Not gonna make any production quotas but who cares?
 
OH, I guess I was assuming these orifices came with a pre-drilled tiny hole that you were simply enlarging.
 
Bruce said:
OH, I guess I was assuming these orifices came with a pre-drilled tiny hole that you were simply enlarging.
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They do. They all come as a "spud". Then you simply size as needed. First time I did one, I walked into a local heating supply, showed them what I wanted, proudly told them what BTU to size them to and all was good. However stupid me, I told them to size them to "total" BTU rather than "per burner". So, IIRC the unit I was converting was 48k BTU total over 3 burners. But, I told them 48K. Needless to say I had a bit of a blow torch :D
Fun times
 
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